In retrofitting facilities with heating and air-conditioning systems, the installation of standard air ducts may be expensive and in some cases impractical. In order to avoid the installation of standard air ducts, fan coil units offer a solution. Particularly, such fan coil units have heating and cooling coils through which heated or chilled liquid is circulated. A fan draws air from the occupied space through an intake opening, moves the air across the heating and cooling coils, and discharges the air back into the occupied space through a discharge opening. The advantage of such a fan coil unit is that the piping for the heated or chilled liquid is substantially smaller than air ducts and can be more easily installed as part of a heating and air-conditioning retrofit. Because the fan coil unit has a fan for circulating the air through the fan coil unit, such fan coil units often produce noise levels within the occupied space that are unacceptably high.
Conventional silencers are typically at least 3 feet in length, usually longer. In such conventional silencers, baffles are arranged based on uniform flow in and out of the silencer. Such conventional silencers are operated with long lengths of straight duct before and after the silencer. Such space is not available for a ceiling mounted fan coil.
Further, conventional fan coil installations typically have connecting ductwork between an inlet silencer and the intake grille and connecting ductwork between an outlet silencer and the discharge diffuser. Such connecting ductwork is required for traditional straight flow silencers, but such connecting ductwork takes up additional space.